How to customize Twig extensions in Symfony?

To customize Twig extensions in Symfony, you can follow these steps:

Create a new extension class: First, create a new PHP class that extends \Twig\Extension\AbstractExtension and implements the Twig\Extension\ExtensionInterface interface. This class will contain all the custom filters, functions, tests, and tags that you want to add to Twig.

namespace App\Twig;

use Twig\Extension\AbstractExtension;
use Twig\TwigFilter;
use Twig\TwigFunction;

class CustomExtension extends AbstractExtension
{
    public function getFilters()
    {
        return [
            new TwigFilter('custom_filter', [$this, 'customFilter']),
        ];
    }

    public function customFilter($value)
    {
        // Custom filter logic here
        return strtoupper($value);
    }
}

Register the extension as a service: Next, register the new extension class as a service in your Symfony project's services.yaml file. This will make the extension available to Twig.

services:
    App\Twig\CustomExtension:
        tags: [twig.extension]

Use the custom extension in your templates: Once the custom extension is registered as a service, you can start using the custom filters, functions, tests, and tags in your Twig templates.

{{ 'hello world' | custom_filter }}

By following these steps, you can easily customize Twig extensions in Symfony and add your own custom functionality to Twig templates.